Is there anyone who has used both who can comment on the pros and cons?
For torrents, I tend to just use rtorrent, which has worked perfectly for me for probably 15 years now. https://github.com/rakshasa/rtorrent. Nice, fast, doesn't seem to use many resources to get the job done.
great tool for downloading subtitles, sadly it seems unmaintained and sometimes fails to work
rtorrent: https://github.com/rakshasa/rtorrent
my preferred way to download ISOs of Linux distributions
And a +1 for some that were already mentioned: tig, ripgrep, htop, midnight commander
With that in mind I can recommend Tmux/Screen + rtorrent (daemon, ncurses) [1] + flood (WebUI) [2] for if you don't have CLI. Works well in Docker.
Plain text, runs in a terminal (which means screen or tmux allows for remote, headless, operation).
No ads, just torrenting.
It fits the efficient, small memory-footprint and no ads requirements. "Full Featured" is subjective as it depends upon what you consider "Full Featured".